Operation; Line Supervision; Impedance Measurement - Bosch PAVIRO PVA-4CR12 User Manual

36 en | Operation
8

Operation

In accordance with the specified and technical details for this product, the controller can be
used to control and monitor a PAVIRO public address and voice alarm systems within the
building installation.
The controller is not a stand-alone device. The following are the minimum requirements for
operation:
1.
2.
3.
4.
5.
6.
8.1

Line supervision

For loudspeaker line supervision three different options are available. They differ in
performance, cost, and suitability for various applications and situations.
In general the device can detect open circuit and short circuit. In case of an open circuit only a
fault message will be generated. In case of a short circuit a fault message will be generated
and the loudspeaker line will be automatically deactivated to avoid influence to other
loudspeaker lines.
8.1.1

Impedance measurement

The PVA-4CR12 controller provides a function to measure the loudspeaker cable impedance.
This function puts a sinus signal on the loudspeaker cable connection and measures the
effective current and voltage. The impedance value of the loudspeaker cable (= cable and
loudspeaker) is calculated based on the measurement results. Impedance measurement can
only be done in non-active loudspeaker cable outputs.
To detect impedance deviations in the loudspeaker cable, caused by an open or shorted cable
connection, a failure-free loudspeaker cable reference value must have been measured and
stored beforehand. All future impedance measurements are only compared against the
impedance reference value. When an impedance value exceeds the accepted and configured
tolerance, a failure is reported.
The calibration of impedance measurement circuits is not necessary because the system only
notices impedance tolerances. In this way, absolute failures of values are mathematically
eliminated.
The measuring frequency and voltage can vary within given borders and can be adapted to the
local conditions, like used loudspeaker types and cables or mains power. In general, it is
recommended not to deviate from given default values. If the frequency is too high, the
measurement signal might be audible. If the frequency is too low, the measured impedance
value may be outside the specified range as lower frequency decreases the impedance of the
loudspeaker's transformer.
2022-11 | 07 | F01U306900
A mains adapter (24 V) sufficiently configured for the system's power demands.
If the device is to be operated with call stations: The required number of call stations
(max. 16) and the corresponding connecting cables.
If the audio element of the device is to be used: Power amplifier incl. cabling and
loudspeaker with cabling.
If the internal real-time clock is to be synchronized to the DCF77 time signal: An active
DCF77 reception antenna incl. cabling. (This feature can be used only in regions in which
the DCF77 signal can be received with sufficient strength, or if converters from different
time information to DCF77 are used.)
If slave clocks are to be controlled: The required number of slave clocks incl. cabling
If additional line relays and/or control inputs or outputs are to be used: A router and the
corresponding connecting cables.
User manual
PAVIRO Controller
Bosch Security Systems